Organic peroxyacid bleaches are well known in the art. At moderate washing temperatures (e.g., 15.degree.-52.degree. C.) they are generally more effective in removing stains from fabrics than are the inorganic peroxide bleaches such as sodium perborate, sodium percarbonate, etc., and they are generally more safe to delicate fabrics and to fabric dyes than hypochlorite bleaches such as sodium hypochlorite and sodium dichlorocyanurate.
Among the organic peroxyacid bleaches, it has been found that those which have a long hydrocarbyl chain with the percarboxylate group at one end (e.g., perlauric acid) tend to be more effective (on an equal available oxygen basis) in bleaching of hydrophobic stains from fabrics than those which are not structured in this way, e.g., peroxybenzoic acid and diperoxydodecanedioic acid.
The long chain peroxyacids with the percarboxylate groups at one end have a structure similar to surface active agents (surfactants). It is believed that in a washing solution, their hydrophobic "tail" tends to be attached to the hydrophobic stains on the fabrics, thereby causing a localized increase in bleach concentration around the stain and thus resulting in increased efficiency in bleaching for a given concentration of active oxygen in the bleaching solution.
Peroxyacids having a long hydrocarbyl chain (C.sub.8 to C.sub.22) with the percarboxyl group at one end will be referred to herein as "surface active" peroxyacid bleaches. By contrast, peroxyacids which have a long hydroxycarbyl chain and a peroxyacid group at each end (e.g., diperoxydodecanedioic acid) are not considered to be surface active.
When peroxyacid bleaches are dissolved in a bleaching liquor in the presence of stained fabrics and hardness ions (i.e., calcium and magnesium) some of the available oxygen is lost from the bleaching process because of decomposition and/or deactivation.
The primary objective of the present invention is to provide means to inhibit the decomposition and/or deactivatoion of surface active peroxyacid bleaches and thereby increase the proportion of available oxygen which can be utilized in the bleaching process.